Stock Compensation Plans - Additional Information (Detail) (USD $)	12 Months Ended					12 Months Ended
	Dec. 31, 2013 OptionPlan	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013 1997 Plan	Dec. 31, 2013 1997 Non-Employee Stock Option Director Plan	Dec. 31, 2013 2004 Plan	Dec. 31, 2013 Restricted Stock	Dec. 31, 2013 2010 Change In Plan	Dec. 31, 2013 2009 Plan	Dec. 31, 2013 Director's Plan, Per Director	Dec. 31, 2012 Director's Plan, Per Director	Dec. 31, 2008 Director's Plan, Per Director
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Compensation Plans	4
Granted awards, authorized				1,400,000	250,000	1,750,000			1,781,546
Common stock, outstanding	814,291	831,504				144,606			669,685
Exercise price, lower range						$ 13.04			$ 24.30
Exercise price, upper range						$ 31.06			$ 57.01
Vesting period, years							3 years		3 years			3 years
Weighted average remaining contractual term	3 years 2 months 12 days						10 years	7 years
The terms for number of shares to be granted upon election												3,400
The terms for number of shares to be granted to director												2,200
The terms for value of shares to be granted upon election										$ 100,000	$ 100,000
The terms for value of shares to be granted to director										80,000	70,000
Allocated Share-based compensation expense	4,409,000	4,080,000	2,756,000
Weighted-average grant-date fair value	$ 14.41	$ 22.28	$ 14.15
Total intrinsic value of stock options exercised	3,700,000	7,100,000	10,400,000
Total fair value of stock options vested	3,300,000	1,700,000	1,600,000
Unrecognized stock-based compensation expense	$ 6,000,000
Weighted average, expected recognition period	2 years 6 months